1. Technical Field
The present disclosure relates generally to the field of plastic containers, and more particularly, to panel stiffening features associated with the side walls of plastic containers.
2. Background of the Related Art
Containers such as those described in the present disclosure are used for storing foodstuffs, medicine, liquids, and many other materials. Certain containers must withstand radial side wall forces and axial top loading forces. For example, certain containers must be rigid enough to resist side wall collapse due to internal vacuums that may develop from storing materials therein. Other containers are required to withstand radial forces during label application operations or axial forces during capping operations.
Plastic containers, specifically blow molded plastic containers, are manufactured in various shapes to achieve structural advantages and aesthetic function. Specifically, it is known to provide container side walls with troughs, extensions and decorative shapes to accommodate internal vacuum forces. Inward flexing of the side walls and panels may also be used. The internal vacuum forces occur, for example, when a container is filled with hot material which cools after the container is sealed. Inward flexing of the side walls accommodate volumetric shrinking but create undesirable corner deformations which reduce structural capability to withstand top loads.
One type of container that provides additional top load strength includes ribbing or reinforcement webs. For example, U.S. Pat. No. 6,016,932 to Gaydosh et al. disclose a blow molded bottle having a reduced diameter portion that divides the bottle side panel into first and second portions. The reduced diameter portion is intersected by longitudinal ribs which support top loading, such as installation of push-up caps, by directing stress between the first and second portions. Containers including ribs require additional material that adds to manufacturing cost. Furthermore, they do not prevent side wall deflection or improve overall rigidity.
Certain types of containers must endure external side loads, for example, during labeling operations, storage and transportation. Other containers must overcome the external side load of a handler""s grip. See, for example, U.S. Pat. No. 5,598,941 to Semersky et al., disclosing a blow molded container including a pair of depressed areas having reinforcing ribs to form a hand grip.
Some containers require annular stiffness to withstand radial forces that occur due to internal vacuum pressure resulting from hot fill material, changes in altitude and absorption of oxygen within the bottle, e.g., by vitamins or other materials which contain oxygen scavenging materials. Concentric annular grooves are commonly used to provide radial stiffness in container structures, such as in lightweight water bottles, made from PET (polyethylene terephthalate). The annular grooves of these lightweight containers reduce the containers"" resistance to top loading, making the containers susceptible to top load crushing.
To overcome this drawback, manufacturers may fabricate the containers with increased wall thickness to provide side load and top load rigidity. Such increased wall thickness, however, requires increased material and mold cycle times, thereby increasing manufacturing cost. Container manufacturers have also attempted to solve strength considerations by including container wall designs to add structural strength. Such designs include decorative shapes and embossed lettering, typically requiring increased material which adds to cost. However, these designs may only provide marginal or incidental increases in structural stiffness.
Therefore, it would be highly desirable to have a simple and economical manner of adding axial and/or side wall deflection rigidity to containers for specific container requirements, shapes and sizes without adding to part complexity or costs of the manufacturing process.
Accordingly, it is therefore an object of the present disclosure to overcome the disadvantages of the prior art by increasing axial and side wall strength and rigidity of plastic containers.
It is a further object of the present disclosure to provide load compensation and increased rigidity of plastic containers in response to externally applied loads.
It is yet another object of the present disclosure, to provide a plastic container that is efficiently and inexpensively manufactured.
Objects and advantages of the present disclosure, set forth in part herein and in part will be obvious therefrom, achieve the intended purposes, objects, and advantages through a new, useful and non-obvious configuration of component elements, at a reasonable cost to manufacture, and by employing readily available materials. The various embodiments contemplated are gleaned from the present disclosure and realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.
The present disclosure is directed to a container structure having increased strength and rigidity due, at least in part, to at least one groove formed in the container. The container, due to the disclosed configuration, facilitates load compensation and stress relief in response to externally applied loads. The container provides increased structural strength to a container while being easily and efficiently manufactured. The container advantageously forms longitudinal stress paths to facilitate load compensation that increases axial stiffness and top-load strength. The structural improvements of the present disclosure are achieved without substantial increases in material costs, mold cycle time or tooling complexity.
In one particular embodiment, in accordance with the present disclosure, a container is provided which includes a top portion having an opening and a side wall extending from the top portion to an end portion of the side wall. The top portion may include a neck portion. A bottom portion is connected with the end portion of the side wall such that the top portion, the side wall and the bottom portion define an interior space of the container. At least one groove is formed in the side wall. At least one groove includes a central arc portion and end arc portions. The central arc portion is substantially concave relative to a longitudinal axis of the container. The end arc portions are substantially convex relative to the longitudinal axis of the container. The end arc portions are formed adjacent ends of the central arc portion and communicate with an outer surface of the side wall. The central arc portion and the end arc portions may be formed having a substantially undulating cross-sectional configuration.
Desirably, the at least one groove includes a plurality of grooves. The plurality of grooves can form rows along the outer surface of the side wall. The rows lie in planes transverse to the longitudinal axis of the container. In an alternate embodiment, the plurality of grooves are disposed within the rows in an interrupted configuration such that at least a portion of the outer surface is disposed between the plurality of grooves. The rows can lie in parallel transverse planes relative to the longitudinal axis of the container. The plurality of grooves may be disposed in the rows in a relative staggered configuration.
In another embodiment, the central arc portion forms a circle having a first radius and the end arc portions form circles having a second radius and a third radius, respectively. The first radius can be greater than the second radius and the third radius. Alternatively, the second radius and third radius may be substantially equal. In another embodiment, the first radius is measured from an axis offset from the longitudinal axis of the container. The at least one groove may be substantially linear or, alternatively, may have a substantially undulating configuration.
The central arc portion and the end arc portions may cooperatively form a load stress path communicating with the outer surface of the side wall for a load applied to the container. The central arc portion can communicate a load stress against a load stress communicated from the end portions along the load stress path. The at least one groove may define a cross-sectional configuration having groove walls extending inward from the outer surface to a groove floor. The groove walls are oriented at a wall angle measured from the outer surface. The wall angle, desirably, measures 90 degrees. The at least one groove can define a cross-sectional configuration having groove walls extending inward from the outer surface to a convergence position such that the at least one groove has a substantially V-shaped cross-sectional configuration.